The invention relates in general to methods for easing the migration of resources from one cloud to another. The solutions proposed relate in particular to methods for replicating data stored on an external cloud on a private storage system. The invention further relates to computerized systems, clouds comprising such computerized systems and computer program products.
A cloud is a set of computer resources organized in such a way that the owner of the resources may dynamically allocate part or all of those resources to users, e.g., for a fixed period of time.
A private cloud is a cloud in which the user and owner belong to the same organization while in an external cloud, e.g., a public cloud, the user and owner belong to a different organization. The cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on-premises or off-premises. Private clouds are preferred when owners or users do not wish to have their computation performed on the infrastructure of a third party, e.g., for reasons of security or reliability. Private clouds have the disadvantage of being inelastic, i.e., the amount of resources that can be allocated to a task is bound by the total amount of resources in the private cloud, which is likely more limited than the amount of resources in a public cloud.
An external cloud as meant herein is typically a public cloud. A public cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services. However, an external cloud as understood herein may also be another private cloud, e.g., having typically more resources than the enterprise private cloud. It may for instance be a Virtual Private Cloud, i.e., a configurable pool of shared computing resources allocated within a public or external cloud environment, and providing some isolation between the different users of such resources.
Cloud computing is a model of service delivery for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g. networks, network bandwidth, servers, processing, memory, storage, applications, virtual machines, and services) that can be rapidly provisioned and released with minimal management effort or interaction with a provider of the service.
Cloud principles are getting more and more attraction. However, one unsolved issue with leveraging clouds relates to the data locality. For example, if a company or an enterprise is running (parts of) its solutions in an external cloud, then corresponding data are inherently moved to the external cloud as well. The daily data transport to the external cloud is usually not a problem as it happens step-by-step, file after file, etc.
However, as it may be realized, if all (or a substantial part of all) the proprietary data needs to integrally return, at some point in time, back to the company (e.g., when changing the cloud provider, or sourcing back in, etc.), then the data volume may typically be significantly too big to be moved in a reasonable amount of time. For example: the transfer a moderate amount of 100 TB of data over a well sized 100 Mbps Ethernet line already takes more than 90 days. Since many companies own and manage hundreds or more of terabytes, while having Internet connections that are often less than 100 Mbps, the actual durations needed to migrate company-wide data is multiplied to an extent where it cannot reasonably be handled.
Cloud providers may provide solutions to this problem. However, such solutions depend on the cloud provider, rather than the companies who need them, and may be onerous.